Vectors t = 3i + 7j, u = 2i 5j, and v = 21i + 9j are given. Part A: Find the angle between vectors t and u. Show all necessary calculations. (5 points) Part B: Choose a value for c, such that c > 1. Find w = cv. Show all necessary work. (2 points) Part C: Use the dot product to determine if t and w are parallel, orthogonal, or neither. Justify your answer. (3 points)